The Center for Soft Matter Research

Soft Matter is a highly interdisciplinary field residing at the interface of conventional disciplines. Significant progresses in the field often require synergistic efforts of scientists, mathematicians and engineers. The Center for Soft Matter Research at Shanghai Jiao Tong University is established to meet this challenge by promoting interactions and collaborations across disciplines.

The center currently consists of nine research groups. Here is a brief introduction to our current research.

Proteins are life engines, carrying out most functions in living things. In the past, most work in molecular biophysics and biochemistry focus on protein structures as the 3-dimensional structures are believed to be the dominating factor to control bio-function. This view has been changing drastically in recent years, as researchers start to realize dynamic motions are also crucial, if not more important than structure, for protein function. However, quantitatively characterizing protein function, especially dynamic pathways for proteins to function at the nanometer length scale, is of great challenge. Prof. Liang Hong and his collaborators combine scattering experiments including X-ray, neutron and light scattering and computer simulation to explore the microscopic interconnection between structure, dynamics and function in various protein systems.

The theoretical group led by Prof. Dan Hu has broad interests in understanding properties of physical and biological systems by modeling, analysis, and simulation. Currently, the main interests of the group focus on 1) designing principles of biological transport networks such as circulation systems and leaf venation, namely, the function and properties of their network structures and physiological processes to form particular network structures.; 2) propagation of blood pulse waves and signal decoding of blood pressure waveforms; 3) interaction between blood flow and blood vessels; and 4) numerical methods for free energy calculation of molecular systems and function and dynamics of membrane-peptide structures.

Jakob Ulmschneider’s research is focused on computationally modeling proteins and peptides associated with, or embedded into the lipid bilayer, and to study their partitioning, folding, and assembly. Channel proteins are vital for cellular survival and handle many of the essential biological functions of cells. Long-timescale equilibrium simulations are used to study the molecular mechanisms underlying channel selectivity, voltage-gating, and ionic flux. Small membrane-active antimicrobial peptides (AMPs) are found in many organisms as part of the immune system to defend the host against invading bacteria by specifically interacting with and disrupting their cell membranes. Our focus is on understanding the mechanism underlying selectivity and activity. The ultimate aim is to design new antimicrobials to combat increasing resistance to small molecule antibiotics that are expensive to develop.

The theoretical group led by Prof. Xiangjun Xing is interested in a variety of theoretical problems relevant to soft matter and statistical physics, including charged many body systems, lipid bilayers, liquid crystals, topological defects, theory of generalized elasticity, disordered medium etc. The members of the group use both analytic and numeric methods to attack these problems.

The research interests of Zhenli Xu’s group generally lie in mathematical modeling and numerical simulations of charged soft materials for their application in engineering and science. The essential component of the research is the development of innovative algorithms motivated by specific scientific problems. The group analyzes the efficiency and scalability of these algorithms and employs them in explaining physical phenomena observed in experiments, such as mechanisms underlying many-body phenomena observed in colloidal suspensions, nanoparticle assembly, and electrochemical energy devices.

Research interest in the theoretical group led by Prof. Zhenwei Yao is understanding exceedingly rich static and dynamic structures arising in the enormous class of soft condensed matter systems using the combination of analytical theory and numerical experiment. ‘Soft matter’ covers a large variety of systems that are far beyond what its name indicates, including polymers, colloids, liquid crystals, surfactants, granular matters, etc. Soft matters are gaining increasing industrial importance. Notably, soft matter based functional materials offer promising opportunity for applications in complex devices and renewable energy. What is equally exciting is new physical concepts and principles to be revealed from intriguing behaviors of soft matters. A common theme in the group’s researches is the crucial role played by geometry and topological defects.

Research interests in Zhang’s lab lie in the areas of soft matter and statistical physics. The lab is interested in fundamental problems which find applications in biological, engineering, and geophysical contexts. The lab’s research involves well-controlled laboratory experiments complemented with theoretical and numerical models to further unveil the underlying physics. Over the past few years, the lab’s research has focused on three closely related topics, namely microswimmer motility, collective motion of active matter, and colloidal dynamics under confinement. These topics all deal with motion and interaction of microscopic particles, which are driven out of thermal equilibrium and strongly influenced by low-Reynolds number hydrodynamics and stochastic noises.

From left to right: spiral particle trajectory in a bacteria pump; acceleration of a bimetallic microswimmer in narrow channels; dynamic clusters in bacteria colony.

Zhang’s lab conducts research of granular physics. Granular materials are ubiquitous in nature and are closely related to many industrial processes and natural hazards. There are many novel and intriguing characteristics in the granular system. The goal of the lab is to uncover deep mysteries of granular materials using table-top experiments. In particular, the lab uses photo-elastic techniques to study the dynamics of granular materials from microscopic “atomic” level all the way up to the macroscopic system size in order to build connections between physics at different scales.